Flaking amorphous solids



y 1936- R. E. ZINN FLAKING AMORPHOUS SOLIDS Filed Sept. 5, 1953 Patented May 19, 1936 UNITED STATES PATENT GFFIGE Robert E. Zinn, Chicago Victor Chemical Work ration of Illinois Application September 5,

Heights, Ill, assignor to s, Chicago, lit, a corpo- 1933, Serial No. 688,26?

Claims. (01. aim-23) This invention relates to the production of thin flakes of amorphous solids.

A method of flaking certain solids is well known in which the solids are heated and thereby dissolved in their water of crystallization and are then spread on the surface of a cool rotating drum, where they solidify, and from which the flakes are scraped. These flakes are generally an agglomeration of tiny crystals, and are of the order of 0.01 of an inch or more in thickness. This method is quite severely limited, since it applies only to salts which can dissolve in their water of crystallization, or can be fused in a very slight excess of water.

A further well-known method of flaking certain substances is to spread solutions or thin pastes of such substances on heated rolls, evaporating the excess moisture, and solidifying the material on the rolls and scraping such material from the rolls in flake form.

By means of the present invention, amorphous anhydrous materials may be readily flaked into extremely thin flakes. For example, alkali meta and pyrophosphates, fused borax, sulphur, phosphorus and the like, which cannot be flaked in the usual manner, may be flaked in accordance with the present invention.

The invention is illustrated diagrammatically in the drawing, in which,

Fig. 1 illustrates rolls for flaking relatively inert materials; and Fig. 2, the apparatus for flaking such materials as phosphorus which must be handled in an inert atmosphere. Both views show broken sectional front elevations of the apparatus in diagrammatic form.

The apparatus consists of the oppositely rotating rolls 3, the direction of rotation being indicated by the arrows. The rolls operate upon the bearings t through which a cooling or heating fluid may be introduced as through the pipes 5 and withdrawn through the pipes 6. Molten material is supplied to the rolls in a stream as indicated at l and a cooling jet 8 may be provided to cool the material leaving the rolls.

In Fig. 2 a housing 9 is provided which may be filled with inert gas through the line H). A pressure relief valve Il may be provided. At the bottom of the housing is indicated a pool of inert liquid I 2 which in the case of phosphorus may be water.

As an example of the present invention, anhydrous sodium metaphosphate was fused at about 700 C., was then pouredbetween two smooth faced steel rolls rotating at about 1200 R. P. M. The product issuing from the rolls has a clear glassy like appearance, and consists of ribbon-like flakes having a thickness of the order of 0.001 of an inch in thickness. These flakes are almost instantly soluble in water, whereas the ordinary sodium metaphosphate even when in powdered form, distinctly resists water solution by forming a gummy agglomeration which resists the penetration of water, so that complete solution may be delayed for hours.

It is preferred to operate the flaking rolls so 10 that the fused metaphosphate is only partially cooled by contact therewith, and complete solidification takes place only after dischar e therefrom. If the rolls are rotated very slowly, or cooling is carried on so rapidly that it is complete before passage of the material between the rolls, a powdered product will result.

The rolls are preferably of small diameter, for example, from three to twelve inches, and are rotated toward each other at speeds normally go from 300 to 1800 R. P. M. While steel rolls have been mentioned, it is understood that they may be made of any suitable material depending upon the nature of the substance to be flaked. The thickness of the flakes may be controlled to a considerable extent by variation of the distance between the rolls and the speed of rotation. The rolls may be cooled in a variety of ways, depending upon the character of the material to be flaked. Generally, such cooling is carried out by circulating water on .the interior of the rolls. However, where it is desired to maintain the rolls at a fairly high temperature, the cooling may be carried out by the use of steam or superheated steam, whereby the proper relative cooling is obtained. For example, in flaking molten glass, it may be highly desirable to use a high roll temperature. This'result may also be accomplished by blowing gases of the desired temperature against the flakes as they are dis- 40 charged from the rolls.

It is to be understood that the material does not adhere to the rolls in this process, and when the term discharging or removing the material is used, it does not imply that the material has to '45 be scraped therefrom, although it is not intended to disclaim such processes.

In the case of materials such as phosphorus, the flaking operation may be carried out in an inert fluid, either gaseous or liquid. '50

The alkali metal meta and pyrophosphates or mixtures thereof, are eflicient water softeners. These phosphates have the property of softening hard waters without the precipitation of the calcium salts. However, as ordinarily prepared,

they are difiicultly soluble in water and therefore are often placed upon the market in a water solution to permit their ready use. Flakes of this material produced by the present method, dissolve extremely rapidly and may be marketed in the solid form. Either the pyro or metaphosphates or mixtures thereof can be successfully flaked.

The process as a whole is chiefly of value in connection with chemically reactive materials, in order to provide a more readily reactive form. By chemically reactive in this sense, is meant not only chemical reactions as ordinarily termed, but reaction such as the solution in water or other liquid. However, the process may also be used with non-reactive material such as glass, with which it will produce flakes which may be used for decorative and other purposes. The flakes are normally produced 015 the order of 0.001 of an inch in thickness. This may be varied within considerable limits, but in general, the flakes are less than 0.01 of an inch in thickness.

By rotating the rolls so slowly as to permit the material to practically completely congeal before being passed between the rolls, the material is powdered to a fine powder. This method may in some instances be useful for powdering chemicals which otherwise are difiicultly powdered, and the powder so produced has somewhat different characteristics than powders produced in the ordinary fashion.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible, in view of the prior art.

Iclaim:

1. As an article of commerce, thin flakes of an article of the class consisting of alkali metal metaphosphates, and alkali metal pyrophosphates, said flakes having a thickness of the order of .001 of an inch.

2. As an article of commerce, a sodium metaphosphate in the form of anhydrous amorphous flakes of the order of 0.001 of an inch in thickness.

3. As an article of commerce, a thin flake of an alkali metal metaphosphate, said flake having a thickness of the order of .001 of an inch.

4. As an article of commerce, a thin flake of an alkali metal pyrophosphate, said flake having a thickness of the order of .001 of an inch.

5. As an article of commerce, a thin flake of a mixture of an alkali metal phosphate and an alkali metal pyrophosphate, the flake having a thickness of the order of .001 of an inch.

ROBERT E. ZINN. 

